Poetry stuff.

src/holt59/aoc/2023/day3.py

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+import string
+import sys
+from collections import defaultdict
+
+NOT_A_SYMBOL = "." + string.digits
+
+lines = sys.stdin.read().splitlines()
+
+values: list[int] = []
+gears: dict[tuple[int, int], list[int]] = defaultdict(list)
+
+for i, line in enumerate(lines):
+    j = 0
+    while j < len(line):
+        # skip everything until a digit is found (start of a number)
+        if line[j] not in string.digits:
+            j += 1
+            continue
+
+        # extract the range of the number and its value
+        k = j + 1
+        while k < len(line) and line[k] in string.digits:
+            k += 1
+
+        value = int(line[j:k])
+
+        # lookup around the number if there is a symbol - we go through the number
+        # itself but that should not matter since it only contains digits
+        found = False
+        for i2 in range(max(0, i - 1), min(i + 1, len(lines) - 1) + 1):
+            for j2 in range(max(0, j - 1), min(k, len(line) - 1) + 1):
+                assert i2 >= 0 and i2 < len(lines)
+                assert j2 >= 0 and j2 < len(line)
+
+                if lines[i2][j2] not in NOT_A_SYMBOL:
+                    found = True
+
+                    if lines[i2][j2] == "*":
+                        gears[i2, j2].append(value)
+
+        if found:
+            values.append(value)
+
+        # continue starting from the end of the number
+        j = k
+
+# part 1
+answer_1 = sum(values)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = sum(v1 * v2 for v1, v2 in filter(lambda vs: len(vs) == 2, gears.values()))
+print(f"answer 2 is {answer_2}")